1. Field of the Invention
The present invention relates to a toner level control device useful in an apparatus for dry printing of information. The apparatus utilizes a drum or other member containing a latent magnetic image or electrostatic image to which toner particles are applied by means of a decorator. The decorator is one or more rotatable rolls immersed in a sump of toner particles which must be replenished. Accurate control of the level of toner in the sump enables more uniform application of toner to the latent image on the drum.
2. Description of the Prior Art
Both Xerography and magnetography are known. Xerography involves: forming an electrostatic charge on a photoconductive material such as selenium; imagewise exposing the photoconductive material to light whereby the exposed areas lose their charge; and applying a pigmented, finely divided, electrically charged powder which is attracted to and held on the electrostatic image. The charged toner image is then transferred to copy paper either with an opposite electrostatic charge or by means of pressure.
In magnetography a magnetic image is formed, and ferromagnetic particles applied thereto which adhere to the magnetized areas of the image. The particles are then transferred to copy paper.
The broad aspect of using the damping action of the material which level is being controlled on a constantly driven sensing element has been used for many years.